1.4 bar low boost and recent owner impressions

auditude at cox.net auditude at cox.net
Tue Jan 27 23:40:18 EST 2004

Hey 200q20v'ers,

I've been enjoying my 200q20v since putting in a different transmission and new clutch stuff.  
These are such nice cars.  Just so comfortable and nice to drive.  I do have a low boost 
issue that I've been working on when I have the time.  I have been using the info at 
http://www.sjmautotechnik.com/20vboost.html, but thought I would post in case anyone 
cared to comment.  

Since I haven't yet put in a real boost gauge (Don't have a spot picked out, and want to have 
it visible.  I'm thinking get another driver side speaker grill to mount it on top of, so I can 
undo it if need be.  Any other suggestions?), and the trip computer display is intermittent, I 
wasn't sure if I still had my low boost problem or not.  Since I've never driven a sorted 
200q20v before, or even sat in one, I wouldn't know.  Well, the computer display decided to 
work just as I was almost home tonight, so I took another short trip to see if it's still 1.4 bar 
max.  It is.

Since the boost gets up to 1.4 bar exactly, I'm thinking it's the ECU not assisting the WG 
spring (instead of a leak or bad turbo).  So far I have replaced the WGFV (it was dead), the 
BPV (it was leaking), and the IC hoses (they weren't Samco's).  I've check for fault codes 
(none currently) and ran the output checks (everything's fine).  I've disconnected the MFTS 
and it didn't make a difference.

While I haven't pinched the lower WG hose to see if the turbo can actually make more 
boost, I think I have it down to a couple things.  The throttle potentiometer, or maybe the 
altitude sensor (how common is its failure?).  I swapped the throttle pot with another one that 
I have, without checking either with the meter (I can't find it right now), and it didn't help.

I think the next things I should do is the resistance check on the throttle pot to see if it is 
faulty (altho' these can be intermittent and therefore hard to effectively test?), and the voltage 
from the altitude sensor.

Other info is that I do have a working check engine light (where can I get new bulb holders 
for this, and the e-brake and door ajar bulbs?  The retaining clips are gone.), and the car 
makes an audible bypass valve noise when I shift.  So I guess to me that means that my 
intake system is holding enough boost pressure to make a noise when it's bypassed, but the 
trip computer tells me that already.  Also, I'm using the correct F5DPOR plugs, the ones 
that came with the car.

The other issues that the car has is a suspension or perhaps loose engine sounding clunk 
when I'm cresting driveways or the suspension is otherwise unloaded or bumped, and when 
it's cold in the morning it can grind a bit going into second.  I haven't changed the tranny 
fluid (despite having the transmission out, yeah, yeah), but plan to.  When it's warm the 
tranny doesn't do this. 

The K24 does have a slight amount of play, both axially and radially.  I noticed a puff of 
smoke upon startup once, and once after a warm restart while taking off I saw some smoke 
in the headlights behind me.  I haven't seen this before or since those instances.  Also, the 
stock michelin man hose was extremely oily when I swapped it out.  I have not cleaned the 
intercooler, retorqued the knock sensors, or messed with the timing.  The ignition wires, cap, 
and rotor are what came with the car.  I  haven't checked the rotor width.

Even with the 1.4 bar, the car is a pleasure to drive.  I almost don't mind the subpar 
performance, since I have some other issues to sort out and don't want to overdrive the car 
as it sits.  Not to mention it probably keeps me out of trouble for now.  =)

I want to sort out the boost issue and those other things mentioned, get some Bilstein's, and 
chip it.  I still have to swap in my eurolights and ultranator, and "maybe" some 1506.140(? 
5ktq fitment) Eibachs (is there a 200q20v-specific part #?).  So far in addition to what I 
already wrote, I've replaced the blower motor and tranny/clutch, cleaned the ISV, tinted the 
windows, and put in V8 tails.  I would like some pearl V8 door handles someday.

Anyway, is there anything I'm missing with the boost issue, and is there anything else I 
should be thinking about with this car?


'91 200q20v, pearl/black comfort, G60's, usually driven daily
'85 4ksq, now an RS2 spec+ 3B project
'86 Coupe GT, now a future MC-1 project
'88 5kcstq, surplus
'88 90, parts
'86 5ktq, parts
'87 5kt, parts

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